• Design defects occur when system components,interaction between system components,interaction between the system component and outside software /hardware ,or users are incorrectly designed.

• If the user's required design is one and we designed in another way this may come under the designing defects.

• In any of the defect classes throughout the testing process we may consider one thing that the users satisfaction is important. 

• This covers defects in the design of algorithms,control,logic,data elements,module interface description and external software/hardware/user interface description.

Design Defect Types:

1. Algorithmic and processing defects

2. Control,logic and sequence defect

3. Data Defects

4. Module interface description defects

5. Functional description defects

6. External interface description defects

1. Algorithmic and Processing Defects:

• These occur when the processing steps in the algorithm as described by the pseudo code are incorrect.

2. Control, Logic and Sequence Defect:

• Control defects occur when the control flow in the pseudo code is not correct.